如何在Vaadin中接收更改字段的输入？ [英] How can I receive the input of the changed fields in Vaadin?

问题描述

我的Vaadin应用程序提供了一个小表格，该表格是可编辑的。

My Vaadin application provides a little table, which is editable.

如果用户在更改某些字段后单击保存按钮，我将收到所有行并将更改后的行保存到数据库中。

If the user - after changing some fields - clicks on the save button, I will receive all the rows and save the changed rows into the database.

// create a bean item container 
val writers: BeanItemContainer[Person] = new BeanItemContainer[Person](classOf[Person])

// create some person objects 
writers.addBean(new Person("Thomas", "Mann",  1929))
writers.addBean(new Person("W. B.",  "Yeats", 1923))
writers.addBean(new Person("Günter", "Grass", 1999))

// create the table incl. the bean item container  
val table: Table = new Table("Nobel Prize for Literature", writers)

// set some options for the table 
table.setImmediate(true)
table.setEditable(true)
table.setValidationVisible(true)

// create the save button
val saveButton = new Button("save") 

// create a table listener 
saveButton.addListener(new Button.ClickListener() {
  def buttonClick(event: com.vaadin.ui.Button#ClickEvent) {
    table.commit()
    val writerList = table.getItemIds.asInstanceOf[Collection[Person]].asScala.toList
    //
    // **THIS WILL NOT WORK** 
    // 
    //   I received always the original rows, without the
    //   user input, but I needs the user input, the changed rows.
    //                           
    //
    for (item <- writerList) {
      println("firstName ====> " + item.getFirstName)
      println("lastName =====> " + item.getLastName)
      println("year==========> " + item.getYear)
    }
  }
});

如何通过用户输入来接收更改的行？是否有必要实施表单？如果是，在这种情况下如何实施表单？

How can I receive the changed rows with the user input? Is it necessary to implement a form? If yes, how I can implement a form in this case?

推荐答案

Vaadin不会跟踪容器中的已修改项。您必须跟踪bean（人）中的修改。对于所有可编辑属性，并在发生更改时设置修改标志。在保存按钮侦听器中，您可以过滤掉所有修改后的项目。

Vaadin does not keep track of modified items in a container. You have to track the modifications in your beans (Person). Define setters for all editable properties and set a modified flag if something changes. In the save button listener you can filter out all modified items.

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